1. Field of the Invention
The present invention relates to an imaging apparatus.
2. Description of the Related Art
For imaging apparatuses, there has been a demand for an increase in S/N and in dynamic range. A method for meeting the demand is disclosed in Japanese Patent Application Laid-Open No. 2004-15701. In this method, a gain applied before AD conversion is switched depending on the size of an analog signal. A higher gain is applied to a smaller analog signal to relatively reduce the adverse effect of possible subsequent noise. This allows the S/N to be improved. An imaging apparatus includes an image processing unit configured to carry out various types of image processing after reading images. For example, in the imaging apparatus in Japanese Patent Application Laid-Open No. 2004-15701, the image processing unit is connected to the latter stage of a noise canceller and a gain mismatch circuit. To carry out processing such as gain correction and shading correction, the image processing unit may require information on at what gain each pixel data has been read. As illustrated in FIG. 1 and FIG. 10 of Japanese Patent Application Laid-Open No. 2004-15701, gain information applied before AD conversion is output to the latter stage as an M-bit signal, separately from output N-bit data.
However, when the image data and the gain information are separately output to the latter stage as in the case of Japanese Patent Application Laid-Open No. 2004-15701, the number of required output lines is increased, and the system becomes complicated.